(1) Field of the Invention
This invention relates to a method and apparatus for measuring critical dimensions in resist for 193 nanometer or 157 nanometer lithography which maintains constant resist shrinkage.
(2) Description of the Related Art
A paper entitled “193 nm resist shrinkage”, by Su et al., Solid State Technology, May 2001, pages 52-54 and 57, describes problems encountered in 193 nanometer lithography due to variable shrinkage of the resist caused by exposure to an electron beam during critical dimension measurement of the resist.
U.S. Pat. No. 6,114,681 to Komatsu describes an automatic focus control system for an electron beam column.
U.S. Pat. No. 5,916,716 to Butsch et al. describes a method for compensating for repeating pattern deviations such as across chip line width variations in e-beam lithography.
U.S. Pat. No. 6,130,432 to Pfeiffer et al. describes a particle beam exposure system with dynamic focusing.
U.S. Pat. No. 5,025,165 to Chen et al. describes a method of using an e-beam lithography system that comprises optical alignment of a semiconductor body to overcome charging problems.
U.S. Pat. No. 6,066,849 to Masnaghetti et al. describes a method and apparatus for generating an image of a specimen with a scanning electron microscope.
A patent application Ser. No. 10/047,266; filed Jan. 14, 2003; entitled “Reducing Photoresist Shrinkage via Plasma Treatment”; and assigned to the same assignee describes using plasma treatment to reduce photoresist shrinkage. The plasma treatment is carried out prior to critical dimension measurement using an electron beam and decreases shrinkage of the photoresist due to the measurement.